1. Field of the Invention
The present invention has for its object to provide a telephone terminal for connection to a telephone line, of which several variants are possible, either technical variants as a function of a telephone network or functional variants in accordance with the service provided by the terminal, comprising more specifically first means for overvoltage protection, second means for accessing the line, third means for processing telephone signals.
The present invention also has for its object to provide independent modules which, in the interconnected state, constitute said telephone terminal.
2. Description of the Prior Art
Telephone terminals are well known at present; in its most simple case it is a conventional telephone set which, viewed from the exterior, comprises a base and a hand-set; the hand-set only comprises a microphone and a loudspeaker connected to the base via a four-wire cord for transmitting audio signals; the base contains all the circuitry necessary for operation of the set; to satisfy the protection standards, which protect both set and the user, some of the circuits are short-circuit proof and/or protected from accidental high voltages coming from the line; other circuits are designed for operating only on low-voltage, which requires a different technology.
Besides the conventional telephone set, the miniaturisation brought about by the contemporary state of the electronic art has made it possible to realise these last few years one-module telephone sets; such a single unit resembles to a certain extent a conventional hand-set but it additionally comprises dialling means and a line interrupter, these two last-mentioned elements replacing the well-known dial and the cradle in the base of the conventional set; thus, the one-module telephone set comprises all the necessary circuitry and can function without a base with a simple cord having a connector for connecting to a wall socket.
In view of the fast evolution of modern techniques, which has more specifically enabled the realisation of one-module sets, these known structures are not without drawbacks.
In one-module or two-module telephone sets it is necessary, as mentioned above, when one wants to change the network to which it is connected, or to change the service it provides, to modify all the sets in both these cases.